A crew member of a Royal New Zealand Airforce helps to look for objects during the search for missing Malaysia Airlines flight MH370.

Two pieces of debris discovered in South Africa and the Mauritian island of Rodrigues are almost certainly from the missing Malaysia Airlines MH370 jetliner, Malaysia's transport ministry said on Thursday.

Flight MH370 disappeared in March 2014 with 239 passengers and crew on board, shortly after taking off from Kuala Lumpur bound for Beijing, in one of the world's greatest aviation mysteries.

Investigators believe someone may have deliberately switched off the plane's transponder before diverting it thousands of miles off course, out over the Indian Ocean.